Right; that's what I meant by "stylistically" — a `--> Mu` can highlight that something is being returned (and that side-effects are not the primary purpose), while nothing indicates that the return value, though it exists, is incidental and probably from "falling off the end" or using `return` as a control-flow jump. On Thu, Oct 4, 2018 at 15:04 Brandon Allbery <allber...@gmail.com> wrote:
> Arguably it should be --> Any, since Mu vs. Any has meaning with respect > to Junctions. But in this case it's just not stating a redundancy. > > The way you'd phrased it makes it sound like it's an explicit > no-meaningful-result, as opposed to 'we don't know or care'. > > On Thu, Oct 4, 2018 at 3:02 PM Trey Harris <t...@lopsa.org> wrote: > >> Ah (replying to both Brandon and JJ since their replies crossed): >> >> So `--> Mu` is not a sufficient and/or correct return constraint for >> things like AT-POS because why, then? >> On Thu, Oct 4, 2018 at 14:56 Brandon Allbery <allber...@gmail.com> wrote: >> >>> I think they meant more like my AT-POS example: the point is the return >>> value, but you can't say ahead of time what type it will have. >>> >>> On Thu, Oct 4, 2018 at 2:48 PM Trey Harris <t...@lopsa.org> wrote: >>> >>>> >>>> >>>> On Thu, Oct 4, 2018 at 02:13 JJ Merelo <jjmer...@gmail.com> wrote: >>>> >>>>> >>>>> >>>>> El jue., 4 oct. 2018 a las 3:36, Trey Harris (<t...@lopsa.org>) >>>>> escribió: >>>>> >>>>>> _All_ routines in Perl 6 return _something._ A lack of a "-->" simply >>>>>> indicates stylistically that the return is not useful because it's >>>>>> whatever >>>>>> "falls off the end". (There's a bit of variance here as I'm not sure >>>>>> it's a >>>>>> convention everyone has followed.) It's equivalent to "--> Mu" because >>>>>> anything that could "fall of the end" is Mu. >>>>>> >>>>> >>>>> No, it means that it's not constrained to a type. It can still return >>>>> something, but it can be anything. >>>>> >>>> >>>> >>>> I get all that, except for the "No" at the front. ;-) >>>> >>>> Or were you talking about the "not useful" bit? Yes, of course in any >>>> given codebase, the lack of a return value has no more or less meaning than >>>> a lack of any constraint. The programmer may not like using constraints at >>>> all and treats Perl 6 like Perl 5 in the respect of wanting arbitrarily >>>> mungible values. >>>> >>>> But the word "stylistically" was important, as I was responding to >>>> Todd's question about the docs—I think a lack of a return value in the docs >>>> (at least, the ones I could come up with in a grep pattern on my checkout >>>> of docs) does tend to indicate that the return is not useful, that the >>>> routine is a "procedure" run for its side effects rather than for >>>> evaluation. >>>> >>>> Is that what you meant? >>>> >>>> If you were saying in "it can still return something, but can be >>>> anything", that "anything ⊃ (is a strict superset of) `Mu`", then I >>>> don't understand, because I thought all values conformed to Mu. >>>> >>>> >>> >>> -- >>> brandon s allbery kf8nh >>> allber...@gmail.com >>> >> > > -- > brandon s allbery kf8nh > allber...@gmail.com >
